Natural Resources Conservation Service Ecological site R041XC322AZ Shallow Upland 12-16" p.z. Last updated: 4/12/2021 Accessed: 10/02/2021 General information Figure 1. Mapped extent Areas shown in blue indicate the maximum mapped extent of this ecological site. Other ecological sites likely occur within the highlighted areas. It is also possible for this ecological site to occur outside of highlighted areas if detailed soil survey has not been completed or recently updated. MLRA notes Major Land Resource Area (MLRA): 041X–Southeastern Arizona Basin and Range AZ 41.3 – Chihuahuan – Sonoran Semidesert Grasslands Elevations range from 3200 to 5000 feet and precipitation ranges from 12 to 16 inches per year. Vegetation includes mesquite, catclaw acacia, netleaf hackberry, palo verde, false mesquite, range ratany, fourwing saltbush, tarbush, littleleaf sumac, sideoats grama, black grama, plains lovegrass, cane beardgrass, tobosa, vine mesquite, threeawns, Arizona cottontop and bush muhly. The soil temperature regime is thermic and the soil moisture regime is ustic aridic. This unit occurs within the Basin and Range Physiographic Province and is characterized by numerous mountain ranges that rise abruptly from broad, plain-like valleys and basins. Igneous and metamorphic rock classes dominate the mountain ranges and sediments filling the basins represent combinations of fluvial, lacustrine, colluvial and alluvial deposits. Associated sites R041XC306AZ Shallow Hills 12-16" p.z. R041XC316AZ Sandy Wash 12-16" p.z. R041XC318AZ Sandy Loam 12-16" p.z. Deep Similar sites R041XA117AZ Shallow Upland 16-20" p.z. R040XA121AZ Granitic Upland 10"-13" p.z. Table 1. Dominant plant species Tree Not specified Shrub (1) calliandra eriophylla (2) krameria erecta Herbaceous (1) bouteloua repens (2) bouteloua eriopoda Physiographic features This site occurs in the middle elevations of the Madrean Basin and Range province in southeastern Arizona, southwestern New Mexico and Chihuahua and Sonora, Mexico. It occurs on gently sloping to moderately steep pediments which flank mountain areas. Numerous small areas of rock out-crop occur throughout areas of this site. Table 2. Representative physiographic features Landforms (1) Mountain valley (2) Pediment Flooding frequency None Ponding frequency None Elevation 3,200–5,200 ft Slope 1–15% Aspect N, E, S Climatic features Precipitation in this common resource area ranges from 12-16 inches yearly in the eastern part with elevations from 3600-5000 feet, and 13-17 inches in the western part where elevations are 3300-4500 feet. Winter-Summer rainfall ratios are 40-60% in the west and 30-70% in the east. Summer rains fall July-September, originate in the Gulf of Mexico and are convective, usually brief, intense thunderstorms. Cool season moisture tends to be frontal, originates in the Pacific and Gulf of California, and falls in widespread storms with long duration and low intensity. Snow rarely lasts more than one day. May and June are the driest months of the year. Humidity is generally very low. Temperatures are mild. Freezing temperatures are common at night from December-April; however temperatures during the day are frequently above 50 F. Occasionally in December-February, brief 0 F temperatures may be experienced some nights. During June, July and August, some days may exceed 100 F. Cool season plants start growth in early spring and mature in early summer. Warm season plants take advantage of summer rains and are growing and nutritious July-September. Warm season grasses may remain green throughout the year. Table 3. Representative climatic features Frost-free period (average) 220 days Freeze-free period (average) Precipitation total (average) 16 in Influencing water features There are no water features associated with this site. Soil features These soils have developed in place on various types of acid igneous to sedimentary parent material. They are shallow to very shallow and non-calcareous. The underlying bedrock is fractured and weathered and may be calcareous in places. Soil surfaces are well covered by small gravels. Plant-soil moisture relationships range from fair to poor for shallow and very shallow soils respectively. Soils mapped on this site include: SSA-661 Eastern Pinal and Southern Gila counties MU's 8 Chiricahua, 71 Oracle & Romero, 83 Lampshire, 86 Surge; SSA-665 Gila-Duncan area MU LuD Luzena; SSA-666 Cochise county NW part MU's 11 Brunkcow & Chiricahua, 70 Romero & Oracle; SSA-667 Santa Cruz area MU's CrD Chiricahua, GhD Graham, LaE Lampshire GrVSL, ScD Schrap very shaly CL; SSA-669 Pima county E part MU's 17 Chiricahua & Lampshire, 25 Deloro & Schrap, 31 Pantak and 52 Oracle; SSA-671 Cochise county Douglas-Tombstone part MU's 18 Brunkcow & Chiricahua, 101 Chiricahua and 132 Schiefflin StVLS; SSA-703 Tohono O'odham Nation MU 46 Oracle & Romero. Table 4. Representative soil features Surface texture (1) Gravelly sandy loam (2) Very gravelly sandy loam (3) Very gravelly loam Family particle size (1) Loamy Drainage class Well drained Permeability class Moderately rapid to moderately slow Soil depth 10–20 in Surface fragment cover <=3" 25–65% Surface fragment cover >3" 0–10% Available water capacity 0.5–2.4 in (0-40in) Calcium carbonate equivalent 0–5% (0-40in) Electrical conductivity 0–2 mmhos/cm (0-40in) Sodium adsorption ratio 0–2 (0-40in) Soil reaction (1:1 water) 6.1–8 (0-40in) Subsurface fragment volume <=3" 15–65% (Depth not specified) Subsurface fragment volume >3" 0–10% (Depth not specified) Ecological dynamics The plant communities found on an ecological site are naturally variable. Composition and production will vary with yearly conditions, location, aspect, and the natural variability of the soils. The Historical Climax Plant Community represents the natural potential plant communities found on relict or relatively undisturbed sites. Other plant communities described here represent plant communities that are known to occur when the site is disturbed by factors such as fire, grazing, or drought. Production data provided in this site description is standardized to air dry weight at the end of the summer growing season. The plant communities described in this site description are based on near normal rainfall years. NRCS uses a Similarity Index to compare existing plant communities to the plant communities described here. Similarity index is determined by comparing the production and composition of a plant community to the production of a plant community described in this site description. To determine Similarity Index, compare the production (air dry weight) of each species to that shown in the plant community description. For each species, count no more than the maximum amount shown for the species, and for each group, count no more than the maximum amount shown for the group. Divide the resulting total by the total normal year production shown in the plant community description. If rainfall has been significantly above or below normal, use the total production shown for above or below normal years. If field data is not collected at the end of the summer growing season, then the field data must be corrected to the end of the year production before comparing it to the site description. The growth curve can be used as a guide for estimating production at the end of the summer growing season. State and transition model Figure 4. State and Transition, Granitic Upland 12-16" pz. State 1 Historic Climax Plant Community Community 1.1 Historic Climax Plant Community Figure 5. Shallow upland 12-16" pz. HCPC This site includes plant communities that naturally occupy the site following fire, drought, flooding, herbivores, and other natural disturbances. The historic climax plant community represents the natural climax community that eventually reoccupies the site with proper management. The potential plant community on this site is dominated by warm season perennial grasses and several species of low shrubs. Perennial forbs and annuals are of minor importance on this site. The aspect is shrub dotted grassland. All of the major perennial grasses and shrubs on the site are well dispersed throughout the plant community. Drought and or fire can open up the grass community for a few years, but the major species of short gramas will quickly recover. The dominant half shrubs on the site are vigorous sprouters after fire. Shrubby buckwheat can diminish in severe drought. Table 5. Annual production by plant type Low Representative Value High Plant Type (Lb/Acre) (Lb/Acre) (Lb/Acre) Grass/Grasslike 250 450 660 Shrub/Vine 100 135 200 Forb 6 10 45 Tree 0 1 10 Total 356 596 915 Table 6. Soil surface cover Tree basal cover 0-1% Shrub/vine/liana basal cover 3-5% Grass/grasslike basal cover 3-10% Forb basal cover 0-1% Non-vascular plants 0-1% Biological crusts 0-1% Litter 15-50% Surface fragments >0.25" and <=3" 25-65% Surface fragments >3" 0-10% Bedrock 1-10% Water 0% Bare ground 5-50% Table 7. Canopy structure (% cover) Grass/ Height Above Ground (Ft) Tree Shrub/Vine Grasslike Forb <0.5 – 0-5% 5-10% 0-1% >0.5 <= 1 – 5-10% 10-25% 0-1% >1 <= 2 – 5-10% 5-10% 0-2% >2 <= 4.5 – 0-5% 0-2% – >4.5 <= 13 0-2% 0-1% – – >13 <= 40 – – – – >40 <= 80 – – – – >80 <= 120 – – – – >120 – – – – Figure 7. Plant community growth curve (percent production by month). AZ4131, 41.3 12-16" p.z. hill sites. Growth begins in the spring, semi- dormancy occurs during the June drought, most growth occurs during the summer rainy season.. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 0 0 5 10 10 0 30 30 10 5 0 0 State 2 Lehmann lovegrass invaded Community 2.1 Lehmann lovegrass invaded Figure 8. Granitic Upland 12-16" pz. Lehmann lovegrass This state occurs where Lehmann lovegrass has invaded from existing stands along roads, trails and rights of ways through areas of the site.